There is a checkbox called "swap" and other called "after" in signals editor. What is their purpose?
https://developer.gnome.org/gobject/stable/gobject-Signals.html#g-signal-connect-swapped
https://developer.gnome.org/gobject/stable/gobject-Signals.html#g-signal-connect-after
I think the docs speak for themselves but an example for after is say you had a dialog that runs something important on the 'response' signal, you would connect after so that has already ran.
Swapped is just for very specific cases where you want to reuse a function.